vertices array in the line geometry, that the length of the vertices array is more than 0.

    - This prevents crashing when a Line object is added to the scene before it has vertices
      added to it.

CTMLoader can now properly load very large models by using now uses BufferGeometry's computeOffsets.

This ensures that all the index buffer uses only 16-bit addressable vertices per draw offset. The previous chunking algorithm referenced in the loader would create a huge amount of draw calls when large meshes would reuse many vertices.
Ref: #3524

computeOffsets() - Reorder the geometry index buffer and attributes so that all indices are referencing a maximum
reorderBuffers() - Reorder and grow the vertex attributes to adhere to a new index map.
Ref: #3524

Helps to unify Frustum checking code.